The invention relates to an electric power tool comprising a battery pack for driving a working tool. The invention also relates to a charging station for the battery pack.
Electric power tools with a drive motor for driving a working tool that have an electronic control unit for controlling and operating the electric drive motor are known. The power tool is supplied with power from the battery pack through the control unit.
Battery packs are comprised of several individual cells wherein, depending on the employed cells, monitoring circuits are provided for detecting operating parameters such as charge state, cell voltage, cell current and/or cell temperature. The data are evaluated appropriately for which purpose a communication line between the control unit and the monitoring circuit is provided. Through this communication line digital data are exchanged between the control unit and the monitoring circuit at a communication voltage level wherein interfaces with a controller are provided for controlling the data traffic through a sending unit and a receiving unit.
Electric power tools such as motor chain saws, cut-off machines, hedge trimmers, grass/brush trimmers or the like are compact devices whose drive technology is provided within a very small space. Despite high battery pack voltage, significant currents occur in operation and induce disturbances or interference in the communication line. In order to avoid this, in addition to mechanical and electric shielding, complex electronic devices are employed in order to differentiate the transmitted data properly from interference data.